1. Field of the Invention
The present invention relates to a keyswitch device suitable for use as an input switch device or in a keyboard device used as an input/output device of, for example, a word processor or a personal computer, and a keyboard device including the keyswitch device.
2. Description of the Related Art
Hereunder, a related X-shaped keyswitch device used in a keyboard device will be described with reference to FIGS. 4 and 5. A mount member 31 is formed of, for example, a metallic plate and comprises a bottom wall 31a, a plurality of relatively long supporting sections 31b, and a plurality of semi-circular arc shaped holding sections 31c. In order to form the supporting sections 31b, cuts are formed in the bottom wall 31a and the cut portions that are joined at two sides are raised. These cut-and-raised portions are disposed side by side and correspond to the supporting sections 31b. In order to form the holding sections 31c, cuts are formed in the bottom wall 31a in a cantilever manner and the cut portions that are joined at one side are raised. These cut-and-raised portions are disposed side by side and correspond to the holding sections 31c, each of which forms a pair with its associated supporting section 31b. A flexible substrate (not shown) having a plurality of stationary contacts is disposed on the top surface of the bottom wall 31a. A movable contact member 33 comprises a cup-shaped movable section 33a, formed of resin or the like, and a contact section 33b, disposed on the upper surface of the inner portion of the movable section 33a. The movable contact member 33, opposing stationary contacts 32, is mounted to the flexible substrate. When the movable section 33a is pushed and moved, the contact section 33b comes into contact with the stationary contacts 32, whereas, when the movable section 33a is released, the movable section 33a returns to its original state by itself, causing the contact section 33b to move out of contact with the stationary contacts 32. A first lever 34 is molded out of synthetic resin and has a U shape. It comprises a pair of arms 34a, a connecting section 34b connected to one end of each arm 34a, and a circular cylindrical engager 34c disposed at the other end of each arm 34a. A second lever 35 is molded out of synthetic resin and has an H shape. It comprises a pair of arms 35a, a connecting section 35b connected to the central portion of each arm 35a, and circular cylindrical engagers 35c and 35d disposed at respective ends of each arm 35a. By positioning the second lever 35 inside the first lever 34 and placing them so that their central portions are aligned, the first and second levers 34 and 35 are rotatably combined in the form of a cross by a rotary shaft 34d, so that the combined form of the first and second levers 34 and 35 has an X-shaped pantograph structure. With the rotary shaft 34d as a fulcrum, the upper sides of the first and second levers 34 and 35 can move vertically. The first and second levers 34 and 35 combined in this manner are mounted to the mount member 31 in the following way. First, as shown in FIG. 4, one end of one arm 35a and one end of the other arm 35a of the second lever 35 are pushed towards each other in the directions of arrows X. With these ends of the arms 35a moved towards each other, the engagers 35c are aligned with their respective holding sections 31c. When, after the alignment, the ends of the arms 35a that have been pushed towards each other in the directions of arrows X are released, the arms 35a return to their original states by themselves, causing the engagers 35c to be engaged inside the respective holding sections 31c. Next, as shown in FIG. 4, one end of one arm 34a and one end of the other arm 34a of the first lever 34 are pushed towards each other in the directions of arrows Y. With these ends of the arms 34a moved towards each other, the engagers 34c are aligned with the respective supporting sections 31b. When, after the alignment, the ends of the arms 34a that have been pushed towards each other in the directions of arrows Y are released, the arms 34a return to their original states by themselves, causing the engagers 34c to be engaged inside the respective supporting sections 31b. In this way, both the first and second levers 34 and 35 are mounted to the mount member 31 with the pairs of arms 34a and 35a in pushed states. When the first and second levers 34 and 35 are mounted to the mount member 31, the movable contact member 33 is positioned below the central portions of the crossing portions of the first and second levers 34 and 35, so that the movable contact member 33 can be pushed by the second lever 35. A keytop 36 is molded out of synthetic resin and has the shape of an inverted boat. It comprises guides 36a and 36b. The guide 36a is a vertical groove disposed at the inner portion of the lower surface of the keytop 36. The guide 36b is a horizontal groove disposed at the inner portion of the lower surface of the keytop 36. The keytop 36 is mounted to and supported by the first and second levers 34 and 35 by fitting the connecting section 34b of the first lever 34 to the guide 36a and fitting the engagers 35d of the second lever 35 to the guide 36b. The one keytop 36 having such a structure, the pair of first and second levers 34 and 35, the movable contact member 33, the stationary contacts 32, and the mount member 31 form one keyswitch device. By disposing a plurality of such keyswitch devices, a keyboard device is formed. Next, the operation of such a related keyswitch device will be given. First, when the top surface of the keytop 26 is pressed, the first and second levers 34 and 35 are pushed, so that, with the rotary shaft 34d as a fulcrum, the first and second levers 34 and 35 are rotated and moved downward. At this time, the engagers 35c of the second lever 35 are rotated while they are held by their respective holding sections 31c, and the engagers 34c of the first lever 34 are slid horizontally while they are supported by their respective supporting sections 31b. At the keytop 36, the engagers 35d of the second lever 35 are slid horizontally inside the guide 36b, and the connecting section 34b of the first lever 34 is slid vertically inside the guide 36a. 
By the downward movement of the first and second levers 34 and 35, the movable section 33a of the movable contact member 33 is pushed downward, causing the contact section 33b to come into contact with the stationary contacts 32, so that the keyswitch device is turned on. Next, when the keytop 36 is released, the movable section 33a returns to its original state, causing the first and second levers 34 and 35 to be pushed back upward. This causes the keytop 36 to move upward, so that the first and second levers 34 and 35 and the keytop 36 return to their original states before being pushed, so that the keyswitch device is turned off.
The keyswitch device having the above-described structure is widely used in, for example, keyboard devices of personal computers. However, size reduction of electronic devices in recent years has resulted in an increased tendency for a demand for smaller and thinner keyswitch devices. However, in the keyswitch device having the structure shown in FIGS. 4 and 5, the rotary shaft 34d serving as the center of rotation of the levers 34 and 35 is at the centers in the lengthwise direction of the levers 34 and 35, the keytop 36 is connected to the top sides of the levers 34 and 35 with the rotary shaft 34d as the center, and the bottom sides of the levers 34 and 35 are connected to the mount member 31, so that, as the levers 34 and 35 are shortened for the purpose of forming a smaller and thinner keyswitch device, a limit in the lengths of the levers 34 and 35 that allow smooth rotation is reached, so that further reduction in size and thickness cannot be achieved. In addition, in the keyswitch device having their levers disposed in the form of an X shape as viewed from a side, when a top peripheral edge of the top surface at a bearing side of the keytop 36 is pressed, the keytop 36 may tilt in directions A and B in FIG. 5, in which case it is pressed without being moved horizontally downward. In such a case, the contact section 33b may not come into contact with the stationary contacts 32 even if the keytop is pressed. Therefore, there is a demand for a keyswitch device which makes it possible to perform a key input operation by reliably causing the contact section to come into contact with the stationary contacts even when a peripheral edge of the top surface of the keytop is pressed by, for example, a finger.
The present invention has been achieved to overcome the aforementioned problems, and has as its object the provision of a keyswitch device which makes it possible to perform a key input operation by reliably causing a contact section to come into contact with a stationary contact even when a peripheral edge of the top surface of a keytop is pressed by, for example, a finger. It is another object of the present invention to provide a keyboard device which comprises the keyswitch device, which can be easily reduced in size, and which can be easily operated.
To these ends, according to one aspect of the present invention, there is provided a keyswitch device comprising a base; a plurality of levers, one side of each lever movably engaging the base; a keytop supported so as to be movable vertically with respect to the base by being engaged with the other side of each lever; and a switch for performing a switching operation as the keytop is moved vertically. In the keyswitch device, rotary shafts for allowing rotation of the respective levers within respective rotational planes are disposed at respective engagers at both sides of the levers. One of the engagers at each lever is a first engager for movably supporting one of the rotary shafts at the base or the keytop. The other engager at each lever is a second engager for rotatably supporting the other rotary shaft. The rotary shafts disposed at the engagers of at least one of the plurality of levers are oriented so as to cross the rotary shafts or rotary shaft lines disposed at the engagers of another lever.
In the keyswitch device having the above-described structure, the rotary shafts of at least one lever supporting the keytop are oriented so that they cross the rotary shafts of at least one other lever. In other words, unlike the related keyswitch device in which two levers are such that a shaft is fixed at the location where they cross, the levers independently engage the base and the keytop. By virtue of such a structure, even if the lengths of the levers are reduced for reducing the size and thickness of the keyswitch device, the operability of the keyswitch device at the time of a key input operation is not impaired, and the keyswitch device can be more easily reduced in size and thickness than the related keyswitch device having an X-shaped supporting structure.
When a peripheral edge of the top surface of the keytop is pressed at the time of a key input operation, the keytop is not moved downward in a tilted state, but is moved downward in a substantially horizontal state. For example, if the case of supporting the keytop by two levers is considered, when, as in the related keyswitch device, the rotary shafts at the keytop side of these levers are disposed parallel to each other, the keytop can tilt in a direction perpendicular to these rotary shafts. However, in the structure of the present invention, tilting of the rotary shafts of one of the levers in the direction of rotation of the rotary shafts is restricted by the other lever whose rotary shafts cross these rotary shafts, so that the keytop is moved vertically in a horizontal state. Therefore, according to the keyswitch device of the present invention, rattling of the keytop in the horizontal direction can be prevented from occurring, and the keytop is moved vertically without being tiled, so that the switch can reliably perform a switching operation at the time of a key input operation.
In a first form, the plurality of levers comprise a first lever, a second lever, and a third lever, with the rotary shafts of the first and second levers being disposed parallel to each other, and the rotary shafts of the third lever being oriented so as to intersect the rotary shafts of the first and second levers. The keyswitch device having such a structure can be easily reduced in thickness. In the keyswitch device, since the keytop is supported by a pair of levers and a lever that intersects these levers, tilting of the keytop when it is moved vertically does not easily occur, so that the switch can reliably perform a switching operation, thereby making it possible to prevent a user from improperly pressing the keyswitch device.
In a second form, when the structure of the first form is used, the engager of the first lever and the keytop and the engager of the second lever and the keytop are disposed outwardly of the engager of the first lever and the base and the engager of the second lever and the base, respectively, the engager of the first lever and the keytop and the engager of the second lever and the keytop are the second engagers that rotatably support the rotary shafts, and the engager of the first lever and the base and the engager of the second lever and the base are the first engagers that movably support the rotary shafts. According to the structure, since a pair of levers are folded below the keytop when the keytop is moved vertically, the keytop can be smoothly moved vertically without being tilted. In addition, the levers do not protrude beyond the width of the keytop.
In a third form, when the structure of the second form is used, at the engager of the first lever and the base and at the engager of the second lever and the base, the rotary shaft of the first lever and the rotary shaft of the second lever engage respective hook-shaped slide bearings disposed at the base, and the rotary shafts of the first and second levers are slidable within a range in which the rotary shafts are guided in the respective hook-shaped slide bearings. According to the above-described structure, since the slide bearings are formed with hook shapes, the rotary shafts of the first and second levers can be easily engaged with the respective slide bearings.
In a fourth form, when the structure of the third form is used, the first lever and the second lever are each sandwiched at a pair of the hook-shaped slide bearings that are disposed at the base and that engage the first and second levers, and the positions of the first lever and the second lever in the lengthwise directions of the rotary shafts are restricted by the respective pairs of the hook-shaped slide bearings. According to the structure, since movement of the first and second levers in the directions of the rotary shafts is restricted, it is possible to effectively restrict rattling of the keytop.
In a fifth form, when the structure of the first form is used, the third lever is sandwiched at a pair of hook-shaped rotary bearings disposed at the base, and the position of the third lever in the lengthwise direction of the rotary shafts is restricted by the hook-shaped rotary bearings. According to the structure, it is possible to effectively restrict rattling of the keytop.
In a sixth form, when the structure of the first form is used, the keytop and the first and second levers are engaged by disposing the shafts of the first and second levers in respective bearings of the keytop, one of the bearings of the keytop is sandwiched by side walls at both sides of the shaft of the first lever, the other bearing of the keytop is sandwiched by side walls at both sides of the shaft of the second lever, and the positions of the bearings of the keytop in the lengthwise directions of the bearings are restricted by the side walls. According to the structure, movement of the keytop engaging the first and second levers can be restricted, so that a keyswitch device which rattles little can be realized.
In a seventh form, when the structure of the first form is used, the keytop and the third lever are engaged by disposing the shaft of the third lever in a slide bearing of the keytop, and the shaft is disposed and slidable on a guide plate disposed at the slide bearing.
In an eighth form, when the structure of the one aspect is used, the keytop comprises a holder engaging each lever and a key cap adhered to the holder. By virtue of such a structure, since the structural members, including the holder, the levers, and the base, can be used as common members regardless of the type of key cap, a keyswitch device which has a wide range of application and which can allow easy replacement of, for example, the key cap can be provided.
In a ninth form, when the structure of the one aspect is used, the levers each comprise a pair of arms and at least one connecting section that connects the arms, the levers have a U shape or a frame shape, and the first engager and the second engager are disposed on respective sides of the arms. By virtue of such a structure, since the switch can be disposed at the inner side of the U-shaped or frame-shaped levers, space can be effectively used, so that size reduction of the keyswitch device can be easily achieved. In addition, since the rotary shafts are disposed so as to pass through the at least one connecting section, the keytop can be kept more firmly in a horizontal state, so that a keyswitch device whose keytop does not tilt easily when it is moved vertically can be provided.
In a tenth form, when the structure of the one aspect is used, the rotary shafts of levers whose rotary shafts cross each other are disposed at right angles. In other words, the keyswitch device has a structure comprising a lever whose rotary shafts are perpendicular to the rotary shafts of another lever. By disposing the rotary shafts of the levers perpendicular to each other, rattling of the keytop in the horizontal direction and tilting of the keytop when it is moved vertically can most effectively be prevented from occurring, so that a keyswitch device having excellent operability can be provided. In addition, when the rotary shafts of the levers are disposed perpendicular to each other, the rotary shafts of the levers can be disposed along a plurality of side edges of the keytop that ordinarily has a square shape in plan view, so that space between the keytop and the base can be more effectively used.
According to another aspect of the present invention, there is provided a keyboard device comprising any one of the above-described keyswitch devices. The keyboard device comprising the keyswitch device of the present invention is such that the keytop of the keyswitch device can be moved vertically in a constantly horizontal state. Therefore, when the keyswitch device is pressed, a key input operation can be reliably performed, so that a keyboard having excellent operability can be provided.